1. Field of the Invention
The present invention relates to wireless communications and, more particularly, to a method and device for identifying the location of subscriber information for a portable communications device (such as a portable telephone) user using a non-geographic number as the only identifying information.
2. Discussion of Background Art
Most wireline telephone numbers are geographic telephone numbers. For example, a fixed communications device, such as a wireline telephone, facsimile (fax) machine, personal computer or the like, has a telephone number with an area code. The area code and the next three numbers of the telephone number (the exchange) contain geographic location information to allow a call directed to the geographic number to be properly channeled through the long distance telephone lines (which may be owned and/or operated by a long distance service provider) to the proper local telephone lines (which may be owned and/or operated by a different, local telephone service provider).
Many wireless communications devices, such as cellular telephones, also have geographic telephone numbers. Because the communications device is portable, it may not always be located in the geographic area indicated by the area code. The exchange may identify a wireless communications service provider. These geographic telephone numbers do, however, provide sufficient information about the wireless subscriber to successfully connect a call.
FIG. 1 is a greatly simplified illustration of a wireless communications network, called a Personal Communications System (PCS) network 100. The PCS is similar to other types of wireless networks and is described to provide background to the following discussion of the invention; it is not intended by any means to limit the invention to use with PCS systems. Indeed, a person skilled in the art will readily appreciate that the invention may be used in many types of communications systems and is particularly suitable for use in wireless communications systems. The PCS 100 includes a signaling network 102, which supports a switched communications network. A switched communications network may be, for example, a public switched telephone network (PSTN) or an Integrated Signaling Digital Network (ISDN). The signaling network 102 is connected to a wireless communications system 104.
An illustrative signaling network 102 includes (among other things) a network database 105, which may be a service control point (SCP). A database called a Home Location Register (HLR) 106 is part of the signaling network. The HLR 106 is connected via link 108 to a Regional Signaling Transfer Point (RSTP) 110. The RSTP 110 is connected via a number of links 112 to several Local Signaling Transfer Points (LSTPs) 114. Each LSTP 114 is connected via a number of local links 116 to a number of switches such as Service Switching Points (SSP) 118. The SSP 118 connects to customer premises to provide for premises equipment, such as a wireline telephone 120. An SSP 118 may also connect to one or more Wireless Switching Centers (WSC), Mobile Switching Centers (MSC), or Radio Port Control Units (RPCU) 122, which are part of the wireless communications system 104. The WSC (or MSC or RPCU) 122 is connected to a number of Base Stations (BS) (or Radio Ports (RP)) 124, which monitor a xe2x80x9ccellxe2x80x9d (or xe2x80x9ccoverage areaxe2x80x9d) 126. One or more WSC 122 are connected to a second database called the Visiting Location Register (VLR) 128.
The HLR 106 contains a database maintained by a user""s local telecommunications service provider at the user""s home location. This database includes information about the user, called the user profile. The VLR 128 is maintained by a telecommunications service provider at the location the portable device user and portable device 130 are visiting. The portable device 130 may be a wireless telephone, a personal digital assistant (PDA) having wireless communication applications, or other device. The VLR 128 stores a subset of the HLR 106 user information, and records that the portable device 130 is currently located in the area serviced by that VLR. The HLR 106 keeps a record of the VLR in which the portable device is currently located. When the portable device 130 travels to an area covered by a different WSC 122, the device is registered in the new WSC 122. The new location is stored in the VLR 128. If the portable device 130 travels to an area covered by another VLR 128, the subset of the HLR 106 data stored in the previous VLR is transferred to the new VLR. The location of the new VLR is stored in the HLR and the previous VLR location is deleted from the HLR 106.
Wireless communications services are provided by wireless communications service providers, which may or may not also be local telephone service providers. Some wireless services, such as proposed PCS service, do not use geographic telephone numbers. Such telephone numbers, called non-geographic (tele)phone numbers or NGPN, do not contain the information identifying the subscriber""s signaling network database, which contains, for example, the service provider""s HLR containing the subscriber""s user profile. They also do not contain the information necessary to identify the service provider serving that subscriber, from which the identity of the signaling network database may be obtained.
Each wireless service provider may have one or more HLRs. Moreover, a service provider may need to add HLRs as it obtains additional subscribers when the current HLR(s) have run out of storage space or the current HLR(s) cannot efficiently process information for all of the subscribers contained in the existing HLRs. Also, a service provider may have HLRs located in a number of geographic locations to reduce communications costs to subscribers having home locations in those geographic regions.
One currently proposed manner in which the appropriate signaling network database is identified from a NGPN is Global Title Translation (GTT). GTT is performed by the local and regional signaling transfer points and translates a subscriber""s NGPN to the identity of the appropriate HLR 106 for that subscriber. These signaling transfer points"" main function is to handle call setup and calls. Use of the LSTP and RSTP resources to perform the NGPN translation ties up valuable signaling resources.
In addition to the drawback of STP resource usage, GTT may not be practical in future communications systems. This is because future communications systems may use asynchronous transfer mode (ATM) networks as the wireline communications network. GTT may not be used because an ATM network will use the same physical network for transmitting signaling messages used to set up calls and for transmitting the calls themselves. (Currently, signaling messages are sent on a signaling network separate from the voice trunk network.) Because the same network will be used for call set up and the actual data transmission, signaling transfer points will not be used in the network, and therefore GTT will not be available.
NGPN translation may be required in many situations. Three of these situations are:
(1) When a subscriber travels from an area covered by a first VLR into an area covered by a second VLR, the HLR must be updated so that calls may be routed to the proper location. The subscriber""s HLR needs to be identified in order to update the user profile.
(2) When a call is directed to the subscriber having a NGPN, the translation is used to locate the HLR so that (a) the portable device may be located, and (b) call delivery optionsxe2x80x94such as call forwarding or call screeningxe2x80x94may be obtained.
3) When a subscriber having a NGPN. originates (places) a call, the translation may be used to identify the subscriber""s HLR so that authentication information and service profile information (such as billing information, long distance carrier, etc.) may be obtained.
The NGPN translation process is initiated when an NGPN is presented to a network entity in one of the above situations. The network entity may be a VLR, SSP, STP, or other xe2x80x9cintelligentxe2x80x9d network entity. For simplicity, the specification generically assumes the NGPN is presented to a VLR. It should be understood that any xe2x80x9cintelligentxe2x80x9d network entity may be suitable.
A practical NGPN translation method should meet several criteria. First, it should be fast and efficient. Second, the translation should be able to be performed by widely distributed network entities, such as VLRs, SSPs, or SCP serving the caller. Third, the translation method should be scalable to handle an increase in the number of subscribers and signaling databases using NGPNs. Fourth, the translation method should be flexible so that changes in the NGPN-to-HLR mapping (such as a subscriber changing service providers, two service providers merging into a single company, the HLR becomes saturated, a subscriber moves to a different geographic location, etc.) may be made dynamically, without halting the service provider""s operation. It may also be desirable for a NGPN translation scheme to permit an independent entity, such as a Numbering Plan Administrator, to chose NGPNs for subscribers without considering how the numbers will map to HLRs (i.e., without regard to service provider, geographic location, etc.).
Therefore, it is an object of the present invention to provide a NGPN translation system that may be used in the absence of signaling transfer points or other entity performing GTT.
It is a further object of the present invention to provide a NGPN translation system that is fast and efficient.
It is yet another object of the present invention to provide a NGPN translation system that may be performed by widely distributed network entities.
It is an even further object of the present invention to provide a NGPN translation system that is scalable.
It is yet even another object of the present invention to provide a NGPN translation system that permits dynamic changes to the mapping.
It is yet even a further object of the present invention to provide a NGPN scheme that allows an independent entity to assign numbers without regard to HLR mapping.
These and other objects of the present invention are provided by translation servers added to the communications network. A translation server is a network entity that contains a NGPN-to-HLR mapping table.
Translation servers (TS) may be configured in several ways. In a first preferred embodiment, the translation server is a single, centralized translation server. A VLR queries the central TS to obtain the appropriate HLR address. In a second preferred embodiment, a number of translation servers may be distributed in the signaling network.
When a number of translation servers are used, a VLR receiving an NGPN should be able to determine which translation server contains the mapping for that NGPN. This may be done in several ways. In a first preferred embodiment, a subscriber that has roamed out of his xe2x80x9chomexe2x80x9d region serviced by his service provider, will have his NGPN presented to the TS of a service provider at his current location (a xe2x80x9cforeignxe2x80x9d service provider). The foreign TS may broadcast a query to all other TSs in the signaling network either simultaneously or in stages. In a second preferred embodiment, a VLR receiving a NGPN performs a hash function on the NGPN. The hash function identifies a translation server. The VLR may then query the translation server and obtain the NGPN-to-HLR mapping.
Where a hash function is used, one preferred embodiment uses an extendable hash function to accommodate the addition of new TSs without changing the VLR operating systems. In another embodiment of the translation servers identified with hash functions, further additional TSs are accommodated by a two stage TS. A VLR forms a first hash function. If a TS has split into a number of TSs, the split TS performs a second hash function to determine the location of the TS having the requested NGPN-to-HLR mapping.
The present invention may also be used where a subscriber uses different service providers for different communications services, such as voice, data, and/or video service. Other applications for the present invention are also possible, such as cell relay address translation, Internet and domain name translations, 800 number translation, and local telephone number mobility.